The easist way to change Tag into field of the measurement structure

Hi, there! We have a measurement filled with the data, and after some latest changes in our backend we need now to remake this mesuasurement, changing one tag into field. This tag was initially filled with the strings like ‘100’, ‘500’, ‘1000’ - in other words with the text which easily can be converted into integer. So, what’s the easist way to:

  1. Change this tag into field
  2. Save the data from this tag and insert the one into new modified measurement, converting the string data into integer.